Investmenst (Changes In Allowance For Credit Losses On Mortgage Loans On Real Estate) (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	$ 161	$ 2
Additions from provision for credit loss expense	4	183
Additions from purchases of PCD mortgage loans on real estate
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	108
Balance as of end-of-period	273	273
Changes in economic assumptions increasing provision	112	183
Accrued interest receivable excluded from credit losses	52	52
Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	88	88
Unfunded Loan Commitment [Member]
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	1	0
Commercial [Member]
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	126
Additions from provision for credit loss expense	3	174
Additions from purchases of PCD mortgage loans on real estate
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	107
Balance as of end-of-period	236	236
Commercial [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	62	62
Residential [Member]
Balance as of beginning-of-year, prior to adoption of ASU 2016-13	35	2
Additions from provision for credit loss expense	1	9
Additions from purchases of PCD mortgage loans on real estate
Additions (reductions) for mortgage loans on real estate for which credit losses were previously recognized	1
Balance as of end-of-period	37	37
Residential [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance as of end-of-period	$ 26	$ 26